1. The Field of the Invention
The present invention is directed to methods and apparatus for monitoring the concentrations of certain substances in the blood of an individual. More particularly, the concentrations of natural and synthetic substances, present in an individual's body or introduced from an external source, are monitored noninvasively through diffusion across epithelial membranes, preferably the mucosal epithelial tissues within the mouth.
2. Technology Review
The blood is routinely tested for various blood constituents in countless medical procedures. This generally involves drawing an actual blood sample from the individual, followed by blood analysis. Typically, blood testing is a prophylactic or subsequent response to some type of disease.
The different types of substances which are routinely tested are quite diverse. One classification of the type of substances which are routinely tested are substances that naturally occur in a human body. This can include protein substances such as amino acids, and carbohydrate substances such as glucose.
Another classification of the type of substances which are routinely tested are substances which are introduced into a human body from an external source. These types of substances may be produced naturally or synthetically. Often, these types of drugs require dose-to-effect monitoring because of their toxic nature and to ensure therapeutic effectiveness. Examples of some types of externally derived substances include but are not limited to alcohol, narcotics, bronchodilators, diuretics, asthmatics, substances of abuse, and intravenous anesthetics.
The most accurate method of determining the presence of a substance in a subject's blood is to actually draw a blood sample and analytically measure it for the presence of the substance. Unfortunately, most individuals dislike giving blood samples. In addition, extraction of blood carries the risk of transmitting diseases, such as AIDS. There are also legal issues which arise from invasively drawing blood against the subject's will. Hence, there is a need for devices and methods for noninvasively measuring the presence of a substance in an individual's blood.
Attempts have been made to monitor the level of a substance in an individual's blood noninvasively. As used in this specification, the term "noninvasive blood substance monitoring" means determining the concentration of a substance in an individual's blood without actually drawing the blood. These attempts to monitor the level of a substance in blood noninvasively have most often taken the form of monitoring an individual's saliva or breath.
Measurement of the content of a substance in an individual's blood by a breathalyzer test may be inaccurate because the proportion of a substance in a person's breath is not always proportional to the amount of the substance in a person's blood stream. For example, a person having consumed an alcoholic beverage within a certain time period (i.e. 15 minutes) will register a higher alcohol content on a breathalyzer device than a simultaneously tested blood monitoring device. A certain amount of time must elapse before alcohol in an individual's expiration will correlate with alcohol in an individual's blood stream.
Likewise, efforts to monitor the level of a substance in the blood of an individual based upon the concentration of the substance in an individual's saliva can prove unsatisfactory. It is possible that saliva can become diluted, more concentrated or otherwise contaminated prior to any testing to monitor the concentration of the substance. The imprecise result of any such factors would thereby yield incorrect results.
Therefore, efforts to monitor the concentration of a substance in the blood of an individual based upon the concentration of the substance in an individual's saliva or breath are avoided because both saliva and breath are subject to factors which can lead to incorrect concentrations of the substance level in a person's blood.
There has also been an attempt in the prior art to monitor the concentration of a substance in the blood of an individual noninvasively by treating dermal layers with enzymes which react with the substance. The concentrations of the substance in the epidermal layers can then be determined by monitoring the enzyme reactions. However, these procedures cannot be considered noninvasive because compounds are introduced into the person's epidermal layers. Additionally, the compounds are allowed to react within the person's body, subjecting the dermal environment to reaction by-products.
In view of the foregoing, it will be appreciated that it would be a significant advancement in the art to develop an apparatus and methods for noninvasively monitoring the presence of a substance in the blood.
It would be another significant advancement in the art to provide apparatus and methods for noninvasively monitoring the concentration of a substance in the blood which accurately and reproducibly correlate with actual concentrations of the substance in the blood.
Also, it would be another significant advancement in the art to provide apparatus and methods for noninvasively monitoring the concentration of a substance in the blood without the possibility of contamination which can produce inaccurate reporting of the actual concentration of the substance in the blood.
Additionally, it would be a significant advancement in the art to provide apparatus and methods for noninvasively monitoring the concentration of a substance in the blood which can be performed rapidly.
It would be yet another significant advancement in the art to provide apparatus and methods for noninvasively monitoring the concentration of a substance in the blood which are not limited to certain individuals, but instead can be applied to a wide variety of individuals.
It would further be a significant advancement in the art to provide apparatus and methods for noninvasively monitoring the concentration of a substance in the blood which can be performed at a location, and at a point in time, where and when an individual is first required to be monitored for the concentration of the substance.
Such apparatus and methods for noninvasively monitoring the concentration of a substance in blood are disclosed and claimed herein.